public <T> AssertThat doWithDataContext(Function<DataContext, T> fn)

        throws Exception {

      CalciteConnection connection =

          (CalciteConnection) connectionFactory.createConnection();

      final DataContext dataContext = CalciteMetaImpl.createDataContext(

          connection);

      try {

        T t = fn.apply(dataContext);

        Util.discard(t);

        return AssertThat.this;

      } finally {

        connection.close();

      }

    }